As the weather warms up, it gets harder to pay attention in class and easier to stare out the window and think about recess. This isn’t the only effect of heat, though. Explore the amazing power of heat with a simple classroom experiment. You’ll need sugar, water, a hot plate, a saucepan, and a candy thermometer.
- Put a little bit of cold water into each of the cups of a muffin tin. Label the divisions with the temperatures listed below, and also prepare a chart with the temperatures and space for descriptions:
37 degrees C
80 degrees C
111 degrees C
116 degrees C
125 degrees C
150 degrees C
- Mix one cup of sugar and one cup of water in a saucepan. Clip a candy thermometer to the side of the pan and set the pan over high heat. Gather students and have them watch the thermometer. When the thermometer shows 37 degrees, carefully take a spoonful of the sugar syrup from the saucepan and drop it into the muffin cup labeled “37 degrees.” Do this for each of the temperatures shown on the muffin cups.
- Putting the syrup into cold water at the temperature points allows you to see how it behaves at each point.
- Turn off the heat. Pour out any remaining syrup. Now have students check the bits of syrup in the muffin cups.
- Write the students’ observations under “description” on the chart above. For each temperature, discuss what the syrup looked and felt like after it cooled in the water. Is it liquid or solid? Hard or soft? What shape does it make? Does it hold the shape or change? Help students develop a clear description of each sample.
- Then discuss the experiment. What happened to the syrup as it became hotter? How did it change? Did the changes show in the saucepan, or only after the syrup cooled off in the water? Can you return the new substances to their former state (sugar and water)?
- Think about other substances that change when they get hotter. What happens to popcorn when it gets hot? Butter? Eggs? Plain water? Develop some predictions about what would happen if other substances were heated in the same way. Have students write predictions for their favorite substances and make a display.
Online resources:
- BrainPop has some simple classroom activities on heat, and a movie that you can share with your classroom if you’re a subscriber.
- Lessonplanspage has a simple lesson on heat conduction.
- NASA has a bunch of classroom resources on heat.
- A more advanced lesson on heat and friction uses model roller coasters to examine heat as energy.
- Hot air balloons are a very fun way to introduce science concepts related to heat.
